Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Error code: 429 - {'error': {'message': 'You exceeded your current quota, please check your plan and billing details. For more information on this error, read the docs: https://platform.openai.com/docs/guides/error-codes/api-errors.', 'type': 'insufficient_quota', 'param': None, 'code': 'insufficient_quota'}}
 ###Tabelas: 
CREATE TABLE monitoring_stations (id INT, name TEXT, location TEXT); INSERT INTO monitoring_stations (id, name, location) VALUES (1, 'Station A', 'Coast of California'), (2, 'Station B', 'Seattle Coast'), (3, 'Station C', 'Florida Keys'); CREATE TABLE oxygen_readings (id INT, station_id INT, reading DATE, level DECIMAL(5,2)); INSERT INTO oxygen_readings (id, station_id, reading, level) VALUES (1, 1, '2022-06-01', 7.5), (2, 1, '2022-06-15', 7.3), (3, 2, '2022-06-05', 7.8), (4, 2, '2022-06-20', 7.6), (5, 3, '2022-06-02', 8.2), (6, 3, '2022-06-17', 8.0);
SELECT station_id, AVG(level) avg_oxygen FROM oxygen_readings WHERE reading >= DATEADD(month, -6, CURRENT_DATE) GROUP BY station_id ORDER BY avg_oxygen ASC FETCH FIRST 2 ROWS ONLY;